Method of producing sheet material



Sept. '15, 1942. D. G. MAGILL METHOD OF.PRODUCING SHEET MATERIAL FiledNov. 13, 1939 INVENTOR Patented Sept. 15, 1942 v 2,296,171 METHOD orraonuomo sass-r MATERIAL Donald G. Maglll, American Can Great Neck, N.Y., asslgnor to ompany, New York, N. Y., a

corporation of New Jersey Application November 1 2 Claims.

The present invention relates to a method of producing sheet or web basematerial irom which fibre containers and the like-may be made and hasparticular referen'ce'to such a material of a laminated andmoistureproof nature.

An obiect o! the invention is the provision of a method 0! producingamoistureproot laminated sheet or web material wherein a film ofmicrocrystalline or amorphous wax is applied to a preferably thincellulosic impervious or impermeable web such as "Cellophane" orglassine or to a noncellulosic impervious web suchas Pliofilm" orKorosear' and this web-applied under pressure and at room temperaturetoa heavier pervious or permeable fibrous base sheet or strip such aschipboard, krait paper, or the like, thereby bond-' ing them together ina manner which extrudes the wax coating on the impervious web into thetop fibre oi the pervious base without penetrating through the wax film,thus efiecting a firm adherence and him continuity between the layers toproduce a laminated moistureprooi web from which containers or the likemay be made.

Another object is the provision of such a method of producing alaminated moistureprooi material wherein the micro-crystalline wax isapplied to the impervious web in a molten state and is cooled to'adegree well below its point 01- solidification prior to the imperviousweb being united with the pervious base strip so that penetration of thewax film by the fibres oi the base stoclc will be prevented when thelayers are pressed together.

Another object isthe provision of a method of this character wherein themicro-crystalline wax.

applied to the impervious web is metered in order to produce anaccurately reduced minimum film capable oi maximum moisture resistance.

Numerous other objects and advantages of the invention will be apparentas it-is better understood irom the'iollowing description, which, takenin connection with the accompanying drawing, discloses a preferredembodiment thereof.

Referring to the drawing: Figure 1 is alongitudinal vertical sectionalview illustrating an apparatus for carrying out the various steps of theinstant method invention, the

' view also showing web layers 0! material in place i in the apparatus;and

, Fig. 2 is an enlarged detail used in the apparatus.

In a preferred embodiment of the invention a preferably thin web A oiimpervious material, such as glassine, Cellophane," or other treatedmaterials, is coated on one surface 0! a metering rod 3, 1939, SerialNo. 304,275

uniform film of micro-crystalline or amorphous wax in a molten statemaintained at approximately 180 F. Immediately after its application totheweb the wax coating is cooled to a degree well below its point ofsolidification, such as for example, to approximately 70 F.

The wax coated impervious web A is then brought' into contact with apreferably heavier pervious fibre base strip B such as chipboard, kraftpaper or the like, with the wax film interposed therebetween. Whilethese layers are so aligned they are subjected atroom temperature 1(approximately 70 F.) to a relatively high pressure of approximately3500pounds. As shown in p the drawing this pressure is exerted at thenip or the rolls. This pressure unites the impervious web A withthepervious strip'or web B in a permanent bond and in a manner whichextrudes the wax film of the impervious web into the intersticessurrounding the top fibres oi the pervious web without the top fibrespenetrating through the wax film. This preserves the continuity of thefilm and thereby insures higher moisture resistance, since the filmremains unbroken, and

at the same time results in a firm adherence between the webs. Such alaminated moistureproot material has been found to be ideal for themanufacture oi fibre containers for holding deliquescent granulated orpowdered products which may be packed and safeguarded against moistureinfecting conditions.

One form of apparatus as disclosed in the drawing for carrying out thesteps of this method invention includes a main frame Ii which at one endis formed with brackets l2 carrying a cross rod II on which a roll ll ofthe impervious web A is mounted. The web A extends over a guide bar itcarried in side brackets ll formed on the frame it and thenpassesthrough a coating device I! which is disposed adjacent the guide bar.

The coating device includes a pair oi upper and lower rollers} i, 22between which the web passes and which serve as feed rollers iorunreeling the web-from its roll it and for advancing it along its path01 travel. These rollers are continuously rotated in any suitablemanner.

The lower teed roller 22 is also used as an applying roller and rotatesin a molten bath of microcystalline or amorphous wax 2'3 retained in areservoir 24' formed as an integral part 01 the main frame ii. Thus asthe roller revolves, it

carries the molten wax up out 01 the reservoirv and applies it to theadvancing web. The quan- I on the web surface.

of that actually needed so that this excess may be reduced to a uniformfilm of predetermined thickness by a metering rod which will behereinafter explained.

The wax before application to the web is maintained in a molten state-bysuitable heating elements disposed under the reservoir. These heatingelements are preferably gas burners 26 which are connected into a mainsupply pipe 21 which leads to a suitable source of gas supply.

The upper feed roller 2| is also used as a pressure roller which pressesthe web against the I applying roller 22. This pressure roller ismaintained in a heated condition to prevent chilling of the newlyapplied hot wax. This heating effect is brought about by the circulationof steam through the roller and suitable circulation pipes 28 connectingwith the interior of the roller are provided for this purpose.

The metering rod hereinbefore mentioned and broadly indicated by thenumeral 3|, is disposed adjacent the web exit side of the coating devicejust explained. This rod includes a preferably round stationary crossbar32 (Fig. 2) the ends of which are carried in brackets 33 bolted to thesidewalls of the wax reservoir 24. The brackets are formed to hold thebar over the reservoir. Around the crossbar there is wrapped in helicalfashion a round wire 34 of predetermined gauge which depends upon thedegree of metering necessary, i. e., the thickness of the film desired.

' This wire when viewed in cross section as in Fig.

2 sets off a plurality of ridges 35 having spaces 36 therebetween.

Thus the freshly wax-coated web A as it leaves the coating device,glides over the metering bar 3| in contact with the helically wound wire34. The wire thus scrapes off all wax except that which passes throughthe openings 36 between the ridges 35 of the wire and thereby leaves aplurality of small parallel and spaced wax ridges The excess wax fallsback into the reservoir. Since the wax is still in a fluid state whenthis metering is done it immediately fiows or spreads laterally into afilm of uniform thickness instead of remaining in the series of parallelridges as might be expected. This scraping action of the metering rodaccurat'ely reduces the wax on the web to a minimum film which iscapable of maximum moisture resistance, this being a predeterminedfactor and obtained in practice by the gauge of the metering wire usedin order to provide the proper size of openings 36.

Cooling of the wax film on the web A is preferably effected by air jets,indicated by the numeral 4i and which are projected against the waxcovered surface of the web as the latter advances along its path oftravel. These air jets issue from a spray head 42 carried on the u perend of an air pipe 43 which extends up through an aperture 44 formed inthe main frame H. The air pipe leads to any suitable source of supply ofcompressed air. A valve 45 in the air pipe is provided to manuallycontrol thevolume of the air passing through the jets 4|.

After the cooling operation of the wax coated web A, this web movesforward to meet the base strip B which is now introduced into the pathof travel of the coated web. The base strip B is preferably unreeledfrom a roll 41 which is supported on a cross-rod 48 carried in the mainframe II. The base strip passes up and over the lower roller of a pairof pressure rollers 52 and thus comes into contact with the advancingwax coated web A and both web layers, in superimposed position,thereupon pass 7 between the rollers;

The rollers 5|, 52 are mounted on cross-shafts 53, 54 carried inbrackets 55 formed on the main frame ll. These rollers are continuouslyro-. tated in any suitable manner. It is these pressure rollers thatexert the high pressure at room temperature on the webs passing betweenand thus unite the web layers in a permanent bond.

The pressure on these rollers may be exerted in any suitable manner.

The single web of moistureproof laminated and bonded material thusproduced and indicated by the numeral 51 is advanced toward thedischarge end of the apparatus and is wound on a reel or discharged toany suitable place of deposit. This discharge of the web as it isproduced is effected by a pairof feed rollers El, 62 between which theweb passes. The rollers are mounted on continuously rotatingcross-shafts 63, 64 which are carried in side frames 65 formed on themain frame ll.

While the drawing and the foregoing descrip-' tion disclose theproduction of a two ply web material by joining the impervious web A andthe pervious fibre base strip B, it should be understood that more thana single web A or a single strip B could be used and a multiple layer orply web material could be obtained if more laminations are desired.Furthermore, either the number of layers of either the web A or B may beincreased without maintaining the same relationship of a single layer Afor a single strip B. This will depend somewhat upon the purpose forwhich the multiple layer stock will be subsequently utilized.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the steps of the processdescribed and their order of accomplishment without departing from thespirit and scope of the invention or sacrificing all of its materialadvantages, the process hereinbefore described being merely a preferredembodiment thereof.

I claim:

1. A method of producing laminated sheets for the manufacture ofmoistureproof fibre containers having an inner impervious layer sheet,which method comprises coating a thin impervious carriersheet selectedfrom a class consisting of rubber hydrochloride, regenerated andhydrated cellulose, and vinyl resin, with an adhesive film of moltenmicro-crystalline wax, cooling said applied film of wax to a degree wellbelow its point of solidification to solidify the same, bringing saidwax coated impervious sheet into contact with a heavier permeablefibrous base sheet with the wax coating interposed therebetween, andthen uniting said sheets by sub ecting them to high pressure topermanently bond said sheets together by means of said adhesive wax filmto produce a laminated moistureproof sheet material for the manufactureof said fibre containers, said pressure being sufllciently high toextrude the solidified wax coating on the impervious sheet into the topfibres of the permeable base sheet, the cooling and solidification ofthe waxpreventing the. top fibres of'said base sheet from penetratingthrough the wax film thereby effecting an adherence and continuity ofwax film between said sheets to produce a composite laminatedmoistureproof sheet.

vious carrier sheet selected from a' class consisting of rubberhydrochloride, regenerated and hydrated cellulose, and vinyl resin, withan adhesive film of molten micro crystalline wax, metering said waxcoating into a film of predetermined uniform thickness, cooling saidapplied film of wax to a degree well below itspoint oi solidification tosolidify the same, bringing said wax coated impervious sheet intocontact v with'a heavier permeable fibrous base sheet with the waxcoating interposed therebetween', and

then uniting said sheetsby subjecting them to high pressure topermanently bond said sheets,

together by means of said adhesive wax film to produce a. laminatedmoistureproof sheet material for the manufacture of said fibrecontainers, said pressure being sufllciently high to extrude thesolidified wax coating on the impervi'ous sheet into the top fibres ofthe permeable base sheet, thecooling and solidification of the waxpreventing the top fibres of said base sheet from penetrating throughthevwax film, thereby effecting an adherence and continuity of waxfilmbetween said sheets to produce a composite laminated moistureproofsheet.

DO NALD G. MAGILL.

